Breaker arm



1953 c. A. NICHOLS ETAL 2,658,129

BREAKER ARM Filed Sept. 27, 1951 34 If T /NVE 0 5 X 3. N7. E 29 3/ CHARLES AN/cfloLs 75x9. 79:10.

fle/voLD 15. Exams y dam, wvfizr A T TOBNE Y5 Patented Nov. 3, 1953 BREAKER ARM Charles A. Nichols and Arnold E. Riggs, Anderson, Ind., assignors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application September 27, 1951, Serial No. 248,502

7 Claims. (01. 200-166) This invention relates to improvements in circuit breakers for ignition timers and more particularly to the lever type.

An object of the present invention is to provide a light durable circuit breaker lever which operates at high speed without chattering or rebounding of the contacts. This object and other objects are accomplished by providing a circuit breaker lever of novel construction and a method of making it. A blank of relatively thin sheet metal of symmetrical shape having holes surrounded by annular flanges at right angles to the plane of the blank is bent on its axis of symmetry to provide a groove and a pair of integral leaves from which the annular flanges extend and which are brought into alignment to provide a hub portion and a longitudinal bead, the hub portion of which receives a bearing bushing. The edges of the leaves are preshaped and bent to provide flanges which extend from the hub to the other or free end of the lever and which extend at right angles to the plane of the leaves. These flanges, which together with the annular flanges and the longitudinal bead stiffen the lever, provide a contact receiving pad at the free end of the lever, and a cam follower rubbing block receiving pad intermediate the ends of the lever. A single rivet is disposed between the leaves and is anchored in the bead and is also embraced by the leaves and a hole provided by the rubbing block pad, attached to said pad the rubbing block and one end of a leaf spring.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embodiment of the present invention is clearly shown.

In the drawings:

Figs. 1 to 3 show the steps of shaping and bending sheet metal prior to forming the lever.

Fig. 4 shows the step of folding the sheet metal about a rivet.

Fig. 5 is a side view of a completed lever.

Fig. 6 is a plan view of the circuit breaker and looking in the direction of arrow 6 of Fig. 5.

Fig. 7 is a sectional view taken on line 1-1 of Fig. 4.

Fig. 8 is a view looking in the direction of arrow 8 of Fig. '7.

Figs. 9 through 11 are sectional views respec tively on lines 9-9, l0l0 and ll-ll of Fig. 7.

A blank is punched from thin sheet metal, for example, .010" thick. The blank is formed with relatively small annular holes 2|, D-shaped holes 22, tongue portions 23, intermediate pads 24, and end pads 25. The circuit breaker lever is formed by a series of machine operations on the blank. The metal blank is first placed in a suitable drawing die, not shown, which operates to force the metal about the openings 2| away from the flat plane of the blank to form a larger opening 2la, as shown in Fig 2, thereby providing hubs or annular flanges 26. The blank is then placed in a suitable fixture to bend the blank on its axis of symmetry, indicated by dotand-dash line X-X, see Fig. 2, to form a concavo-convex groove 2'! with integral leaves 28 diverging on opposite sides of the groove 21. The leaves '28 are bent on a line which passes through the openings 22 to provide flanges 29, which extend from the hub of the lever to the tip thereof and includes the pads 30, 25 at right angles to the plane of the leaves. The leaves 28 are bent across the holes 22 so that each pad 29 will have a semi-circular opening 22a the other portion of the holes 22 are shown at 22b in leaves 28, see Fig. 3. A rivet 32 is provided with a wedgeshaped head 33 at one end. The lever thus far formed and the rivet 32 with the wedge-shaped head engaging the bottom of the groove 21 and shank of the rivet opposite the openings 22a and 221) are placed in a suitable fixture. This fixture forces the leaves 28 against each other. As the leaves approach each other the semicircular groove 21 is changed to a tubular bead 3| which extends from the hub portion of the lever to a point below the pads 30 as is apparent in Fig. 8. This fixture also forces the leaves against each other so that the marginal walls of the semicircular openings 22a in pads 29 together embrace the rivet above the wedge-shaped head 33. While the pads 29 are brought together the pads are bent to form permanent flanges 34 which are at right angles to the plane of the pad. The fixture is also shaped so that as the leaves come together the portions of the leaves opposite the rivet and below the opening 220. are worked or deformed over the wedge-shaped head 33 and around the shank of the rivet. The deformation of the metal around the head 33 and the shank of the rivet is permanent so as to prevent the rivet from rotating and moving axially with respect to the leaves 28.

The assembly of lever and rivet is copper plated and is placed in a fixture which holds the contact receiving pads 30 in a horizontal plane facing upwardly. A contact disc, preferably tungsten, is placed upon the pads 30 and this assembly is heated in a hydrogen atmosphere to a temperature sufficient to cause the copper plate to alloy with the parts of the assembly and thus having holes for receiving the upper end of thep; rivet are assembled on the pads 29 and the free end of the rivet is deformed-at 45 overthe spring to secure it and the block to the padslfi. The rubbing block 42 fits between the flanges 34 so that it cannot turn on the riveti, Thespring. is provided with an elongated opening 45 to receive the ears 23 as illustrated in Fig. 2 to prevent the spring from turning on the rivet. Theother end or the spring is provided with a notchadapted to reoeivea suitable terminal support.

It is particularly pointed out that the side flanges-mextend from the hub of the lever to the tip thereof and that the bead also extends from the hub and almost to the tip thereof. This formation of the flanges and bead contribute materially to the rigidity of the lever and thereby make it possible to makea satisfactory lever of sheet steel having a thickness as low as .010 inch. Further, it is pointed out that due to the fact that the spring 43 and block 52 are secured by a single rivet, that this construction will reduce contact bounce or chattering at high speed, for example-at 2500 R. P; M. ignition timer cam speed or 5000 R. P. M. engine speed.

It will be. observed by the above disclosure that a circuit breaker assembly has been provided that is of'light weight, of rigid construction and one that can be easily manufactured with the minimum constructional operations.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be ad t .v

Whatis claimed is as follows.

1. A circuit breaker arm formed from a blank of sheet metal to provide a pair of longitudinally extending leaves joined. by a bead; and means for mounting a rubbing block on said arm comprising a rivet disposed between said leaves and having anexpanded portion disposed against the inside of said bead.

2., A circuit breaker arm formed from a blank over saidwedge-shaped endand-also around the shank-of the rivet,.anchoringthe rivettothe arm.

3. A circuit breaker arm formed from abiank of, sheet metal to provide a pair of longitudinally extending .leave joined by a ,bead, a'hub, and

iii

two oppositely disposed plane flanges to support a rubbing block, a rivet disposed between the flanges and the leaves and having a flattened end extending into the bead, and portions of the sheet metal of the leaves bent about the flattened end of the rivet and portions of the leaves and flanges bent around the shank of the rivet, anchoring said rivet to said arm.

4. A circuit breaker arm formed from a blank of sheet metal to provide a pair of juxtaposed longitudinally extending leaves joined by a bead, a hub, and a flat pad to support a rubbing block; a rivet disposed between the leaves and having a wedged-shaped end extending into the bead, the sheetar'netal of the leaves to be bent over said wedged-shaped end and also around the shank of. saidwrivet, anchoring the rivet to the arm; andan apertured rubbing block fitting over the rivet which is peened over the block to secure the block to said arm.

5. A circuit breaker arm formed-from ablank of sheet metal to providea pair ofiuxtaposed longitudinally extending leaves J'oinedby a bead, a hub, anda flat pad'to support a rubbing block; a rivet disposed between the leaves-and having a wedged-shaped end extending into the head, the sheet metal of the leaves-being forced against each other thereby causing portions of'the sheet metal of the leaves to be bentover said wedgedshaped endand also aroundthe shankof' said rivet, anchoring therivet to the arm; and an aperturedrubbing block and an-apertured leaf spring fitting over the rivet which is peened over spring tosecure the rubbingblock and the spring to said arm.

In a circuit breaker; a rubbing block; means for mounting the rubbing block", said means com prising a stud 'h'avinga flattened end andra'folded arm of sheet metalhavingportions' thereof tightly crimped aboutjsaid flattened end and. the shank of the stud.

"I. The method of making a circuit breaker arm. from ya symmetrical, blank and 'of anchoring a rivet to said arm including. the steps of, bending theblank on its axisof symmetry to form asemi-circular groove and'two divergingv leaves and simultaneously bending portions of the leaves remote from the axis of symmetry, to provide outwardly, extending, flanges atright angles to the plane of said leaves, placing a rivet between the leaves and opposite said flanges which has a. flattened end at one end which engages the bottom of thegroove, forcing the leaves together causing a portion of the metal of. the leaves to be tightly crimped. overthe flattened and also around the shank of the rivet whereby the rivet is held against rotary and-axial movement relative to the leaves.

CHARLES A. NICHOLS:

ARNOLD E; RIGGS..-

References Cited in the file of this patentv UNITED STATES PATENTS Number Name Date 1,851,568 Davis Mar; 29, 1932 2,025,191 Davis Dec. 24; 1935 2,290,078

Thomas Ju1y.14-,'l94*2 

